Clinical studies of camptothecin and derivatives

Peptide-Drug Conjugates as Next-Generation Therapeutics: Exploring the Potential and Clinical Progress

Peptide-drug conjugates (PDCs) have emerged as a next-generation therapeutic platform, combining the target specificity of peptides with the pharmacological potency of small-molecule drugs. As an evolution beyond antibody-drug conjugates (ADCs), PDCs offer distinct advantages, including enhanced cellular permeability, improved drug selectivity, and versatile design flexibility. This review provides a comprehensive analysis of the fundamental components of PDCs, including homing peptide selection, linker engineering, and payload optimization, alongside strategies to address their inherent challenges, such as stability, bioactivity, and clinical translation barriers. Therapeutic applications of PDCs span oncology, infectious diseases, metabolic disorders, and emerging areas like COVID-19, with several conjugates advancing in clinical trials and achieving regulatory milestones. Innovations, including bicyclic peptides, supramolecular architectures, and novel linker technologies, are explored as promising avenues to enhance PDC design. Additionally, this review examines the clinical trajectory of PDCs, emphasizing their therapeutic potential and highlighting ongoing trials that exemplify their efficacy. By addressing limitations and leveraging emerging advancements, PDCs hold immense promise as targeted therapeutics capable of addressing complex disease states and driving progress in precision medicine.

Assessing genotoxic effects of chemotherapy agents by a robust in vitro assay based on mass spectrometric quantification of γ-H2AX in HepG2 cells

Chemotherapy has already proven widely effective in treating cancer. Chemotherapeutic agents usually include DNA damaging agents and non-DNA damaging agents. Assessing genotoxic effect is significant during chemotherapy drug development, since the ability to attack DNA is the major concern for DNA damaging agents which relates to the therapeutic effect, meanwhile genotoxicity should also be evaluated for chemotherapy agents' safety especially for non-DNA damaging agents. However, currently applicability of in vitro genotoxicity assays is hampered by the fact that genotoxicity results have comparatively high false positive rates. γ-H2AX has been shown to be a bifunctional biomarker reflecting both DNA damage response and repair. Previously, we developed an in vitro genotoxicity assay based on γ-H2AX quantification using mass spectrometry. Here, we employed the assay to quantitatively assess the genotoxic effects of 34 classic chemotherapy agents in HepG2 cells. Results demonstrated that the evaluation of cellular γ-H2AX could be an effective approach to screen and distinguish types of action of different classes of chemotherapy agents. In addition, two crucial indexes of DNA repair kinetic curve, i.e., k (speed of γ-H2AX descending) and t50 (time required for γ-H2AX to drop to half of the maximum value) estimated by our developed online tools were employed to further evaluate nine representative chemotherapy agents, which showed a close association with therapeutic index or carcinogenic level. The present study demonstrated that mass spectrometric quantification of γ-H2AX may be an appropriate tool to preliminarily evaluate genotoxic effects of chemotherapy agents.

Phytochemicals as Chemo-Preventive Agents and Signaling Molecule Modulators: Current Role in Cancer Therapeutics and Inflammation

Cancer is one of the deadliest non communicable diseases. Numerous anticancer medications have been developed to target the molecular pathways driving cancer. However, there has been no discernible increase in the overall survival rate in cancer patients. Therefore, innovative chemo-preventive techniques and agents are required to supplement standard cancer treatments and boost their efficacy. Fruits and vegetables should be tapped into as a source of compounds that can serve as cancer therapy. Phytochemicals play an important role as sources of new medication in cancer treatment. Some synthetic and natural chemicals are effective for cancer chemoprevention, i.e., the use of exogenous medicine to inhibit or impede tumor development. They help regulate molecular pathways linked to the development and spread of cancer. They can enhance antioxidant status, inactivating carcinogens, suppressing proliferation, inducing cell cycle arrest and death, and regulating the immune system. While focusing on four main categories of plant-based anticancer agents, i.e., epipodophyllotoxin, camptothecin derivatives, taxane diterpenoids, and vinca alkaloids and their mode of action, we review the anticancer effects of phytochemicals, like quercetin, curcumin, piperine, epigallocatechin gallate (EGCG), and gingerol. We examine the different signaling pathways associated with cancer and how inflammation as a key mechanism is linked to cancer growth.

Molecular Engineering of Peptide–Drug Conjugates for Therapeutics

In recent years, hundreds of novel small molecular drugs used for different treatments have been studied in the three phases of clinical trials around the world. However, less than 10% of them are eventually used due to diverse problems. Even some traditional drugs that have been approved by the Food and Drug Administration (FDA) have faced similar dilemmas. For instance, many drugs have poor water solubility, are easily hydrolyzed, or possess undesirable toxicity, while a variety of cancer cells develop drug resistance (DR) or multiple drug resistance (MDR) towards chemotherapeutic agents after long-term therapy. In order to improve the efficacy and efficiency of drugs, research has been directed forward towards the creation of assemblies of peptide–drug conjugates (PDCs) which have proven to possess wide potential for overcoming such complications based on their excellent biocompatibility, controllable biodegradability, site-selective targeting, and comparably low cytotoxicity. In this review, we focus on the recent developments and advances made in the creation of self-assembled nanostructures of PDCs for cancer therapy, on the chemical and physical properties of such drugs and peptides, and how they are arranged together to form diverse supramolecular nanostructures. Additionally, we cover certain mechanisms regarding how peptides or their derivatives enhance the efficiency and efficacy of those selected drugs and provide a brief discussion regarding the perspectives and remaining challenges in this intriguing field.

Development of Natural Bioactive Alkaloids: Anticancer perspective

Cancer is a frightful disease that still poses a 'nightmare' worldwide, causing millions of casualties annually due to one of the human race's most significant healthcare challenges that requires a pragmatic treatment strategy. However, plants and plant-derived products revolutionize the field as they are quick, cleaner, eco-friendly, low-cost, effective, and less toxic than conventional treatment methods. Plants are repositories for new chemical entities and have a promising cancer research path, supplying 60% of the anticancer agents currently used. Alkaloids are important chemical compounds that serve as a rich reservoir for drug discovery and development. However, some alkaloids derived from natural herbs display anti-proliferation and antimetastatic activity on different forms of cancer, both in vitro and in vivo. Alkaloids have also been widely formulated as anticancer medications, such as camptothecin and vinblastine. Still, more research and clinical trials are required before final recommendations can be made on specific alkaloids. This review focuses on the naturally-derived bioactive alkaloids with prospective anticancer properties based on the information in the literature.

Recent Advances in Improved Anticancer Efficacies of Camptothecin Nano-Formulations: A Systematic Review

Camptothecin (CPT), a natural plant alkaloid, has indicated potent antitumor activities via targeting intracellular topoisomerase I. The promise that CPT holds in therapies is restricted through factors that include lactone ring instability and water insolubility, which limits the drug oral solubility and bioavailability in blood plasma. Novel strategies involving CPT pharmacological and low doses combined with nanoparticles have indicated potent anticancer activity in vitro and in vivo. This systematic review aims to provide a comprehensive and critical evaluation of the anticancer ability of nano-CPT in various cancers as a novel and more efficient natural compound for drug development. Studies were identified through systematic searches of PubMed, Scopus, and ScienceDirect. Eligibility checks were performed based on predefined selection criteria. Eighty-two papers were included in this systematic review. There was strong evidence for the association between antitumor activity and CPT treatment. Furthermore, studies indicated that CPT nano-formulations have higher antitumor activity in comparison to free CPT, which results in enhanced efficacy for cancer treatment. The results of our study indicate that CPT nano-formulations are a potent candidate for cancer treatment and may provide further support for the clinical application of natural antitumor agents with passive targeting of tumors in the future.

Development of Nanoscale Oil Bodies for Targeted Treatment of Lung Cancer

Lung cancer is the most widespread disease and is frequently associated with a high level of epidermal growth factor receptor (EGFR). This study was thus conducted to provide a proof-of-concept approach for targeted therapy of lung cancer by development of nanoscale oil bodies (NOBs). This was carried out by fusion of anti-EGFR affibody (Z_EGFR2) with oleosin (Ole), a structure protein of plant seed oils. The fusion protein (Ole-Z_EGFR2) was produced in Escherichia coli. NOBs were spontaneously assembled from plant oil, phospholipids, and Ole-Z_EGFR2. Consequently, Ole-Z_EGFR2-based NOBs were selectively internalized by EGFR-positive lung cancer cells with an efficiency exceeding 90%. Furthermore, the hydrophobic anticancer drug, camptothecin (CPT), was encapsulated into Ole-Z_EGFR2-based NOBs. The administration of the CPT formulation based on NOBs resulted in a strong antitumor activity both in vitro and in vivo.

Functionalized nanoscale oil bodies for targeted delivery of a hydrophobic drug

Effective formulations of hydrophobic drugs for cancer therapies are challenging. To address this issue, we have sought to nanoscale artificial oil bodies (NOBs) as an alternative. NOBs are lipid-based particles which consist of a central oil space surrounded by a monolayer of oleosin (Ole)-embedded phospholipids (PLs). Ole was first fused with the anti-HER2/neu affibody (Ole-ZH2), and the resulting hybrid protein was overproduced in Escherichia coli. ZH2-displayed NOBs were then assembled by sonicating the mixture containing plant oil, PLs, and isolated Ole-ZH2 in one step. To illustrate their usefulness, functionalized NOBs were employed to encapsulate a hydrophobic anticancer drug, Camptothecin (CPT). As a result, these CPT-loaded NOBs remained stable in serum and the release of CPT at the non-permissive condition exhibited a sustained and prolonged profile. Moreover, plain NOBs were biocompatible whereas CPT-loaded NOBs exerted a strong cytotoxic effect on HER2/neu-positive cells in vitro. Administration of xenograft nude mice with CPT-loaded NOBs also led to the regression of solid tumors in an effective way. Overall, the result indicates the potential of NOBs for targeted delivery of hydrophobic drugs.

From traditional Chinese medicine to rational cancer therapy

Many natural products and derivatives thereof belong to the standard repertoire of cancer chemotherapy. Examples are Vinca alkaloids, taxanes and camptothecins. In recent years, the potential of natural products from plants, notably from medicinal plants used in traditional Chinese medicine (TCM), has been recognized by the scientific community in the Western world. To provide an example of the most recent developments in this field, we have selected several compounds, namely artesunate, homoharringtonine, arsenic trioxide and cantharidin, that are found in natural TCM products and that have the potential for use in cancer therapy. Controlled clinical studies have shown that homoharringtonine and arsenic trioxide can exert profound activity against leukaemia. Increased knowledge of the molecular mechanisms of TCM-derived drugs and recent developments in their applications demonstrate that the combination of TCM with modern cutting-edge technologies provides an attractive strategy for the development of novel and improved cancer therapeutics.

Sequential administration of irinotecan and cytarabine in the treatment of relapsed and refractory acute myeloid leukemia

PURPOSE

Based on reported synergy of the topoisomerase-I (topo-I) inhibitor irinotecan with antimetabolites, irinotecan and cytarabine (Ara-C) were administered sequentially to patients with acute myeloid leukemia (AML) refractory to or relapsed following high-dose Ara-C and anthracycline therapy. Pharmacokinetic and pharmacodynamic studies were performed with the first irinotecan dose.

EXPERIMENTAL DESIGN

In vitro synergy of irinotecan followed by Ara-C was confirmed in a human AML cell line as a basis for the clinical trial. Irinotecan was administered daily for 5 days, with Ara-C 1 g/m2 12 h after each irinotecan dose. Irinotecan was initiated at 5 mg/m2, and the dose was escalated by 5 mg/m2 increments in cohorts of three patients and in individual patients. Pre-treatment samples were studied for topo-I activity and serial samples after the first irinotecan dose were analyzed for pharmacokinetics and for pharmacodynamic effects, including DNA damage and DNA synthesis rate.

RESULTS

The irinotecan dose reached 15 mg/m2 in three-patient cohorts without reaching the maximum tolerated dose, and reached 30 mg/m2 in individual patients. The AUC and Cmax of both irinotecan and its active metabolite SN38 increased linearly in proportion to dose, and the mean half-lives of irinotecan conversion to SN38 and SN38 elimination were 6.2 h (CV 171%) and 7.2 h (CV 48%). Irinotecan rapidly induced DNA damage, and DNA synthesis inhibition varied among patients and treatment cycles. All courses resulted in rapid cytoreduction, and two patients achieved complete remission. Topo-I activity did not predict response.

CONCLUSION

Irinotecan can be safely administered with Ara-C. This combination is active in refractory AML and warrants further study.

Molecular characterization of two anthranilate synthase alpha subunit genes in Camptotheca acuminata

The potent anticancer and antiviral compound camptothecin (CPT) is a monoterpene indole alkaloid produced by Camptotheca acuminata. In order to investigate the biosynthetic pathway of CPT, we studied the early indole pathway, a junction between primary and secondary metabolism, which generates tryptophan for both protein synthesis and indole alkaloid production. We cloned and characterized the alpha subunit of anthranilate synthase (ASA) from Camptotheca (designated CaASA), catalyzing the first committed reaction of the indole pathway. CaASA is encoded by a highly conserved gene family in Camptotheca. The two CaASA genes are differentially regulated. The level of CaASA2 is constitutively low in Camptotheca and was found mainly in the reproductive tissues in transgenic tobacco plants carrying the CaASA2 promoter and beta-glucuronidase gene fusion. CaASA1 was detected to varying degrees in all Camptotheca organs examined and transiently induced to a higher level during seedling development. The spatial and developmental regulation of CaASA1 paralleled that of the previously characterized Camptotheca gene encoding the beta subunit of tryptophan synthase as well as the accumulation of CPT. These data suggest that CaASA1, rather than CaASA2, is responsible for synthesizing precursors for CPT biosynthesis in Camptotheca and that the early indole pathway and CPT biosynthesis are coordinately regulated.